1. Field of the Invention
This invention relates to a posture-improving seat cradle that, in a preferred embodiment, is pivotally connected and rotatable relative to a stand connected to the ground or to a yoke connected to a chair base. The rotatable seat cradle is configured to unload a user's upper body weight from his pelvic sacroiliac joints while promoting a neutral spine sitting posture and inducing anterior pelvic tilt and lumbar lordosis so as to maximize the user's comfort and posture while seated.
2. Background Art
Back pain is an epidemic health problem suffered by a majority of individuals at some point in their lives. The American Academy of Pain Medicine estimates that back pain costs Americans billions of dollars yearly, with back pain second only to the common cold in office visits to the doctor. It has long been known that back pain is one of many side effects attributed to prolonged sitting posture. Neutral spine posture is considered by experts in the field of ergonomics to be the optimal sitting posture. Anatomically, neutral spine posture is defined as the optimum spinal curvature wherein the cervical and lumbar divisions of the spine are moderately convex anteriorly (lordosis) and the thoracic and sacral divisions of the spine are moderately convex posteriorly (kyphosis).
In an unaided and unconscious seated posture, the tendency is for the sitter's pelvis to rock posteriorly on the seat surface, secondary to the sacral kyphosis, thereby initiating a reflex alordosis of the lumbar spine. Alordosis of the lumbar spine induces reflex concomitant postural compensations of both the thoracic and cervical spine divisions potentially leading to upper back and neck pain. It is well documented that alordosis of the lumbar spine results in a shift of the body's center of gravity forward of the neutral postural gravity line, thereby adversely loading the lumbar spine disc structures and predisposing the sitter to lower back pain. Many working in the field of ergonomics agree that neutral spine posture is the optimum sitting posture. Many also agree that neutral spine posture is facilitated by promoting both anterior pelvic tilt and lumbar lordosis. Traction of the spine has long been generally accepted as an effective method for alleviating back pain. Traction of the spine unloads the soft and hard tissue structures of the spine thereby relieving these tissues from the compressive forces associated with prolonged sitting which may relieve the pain associated therewith.
As far as can be determined, a rotatable seat cradle is unknown having a leg support front portion inclined upwardly from a pelvic support intermediate portion and further including a lumbar spine support back portion such that a rotation of the seat cradle in response to a forward leaning sitter promotes dynamic anterior pelvic tilt and dynamic lumber lordosis while simultaneously unloading the sitter's upper body weight from his pelvis for effectively positioning of the sitter's back towards a neutral spine seated posture.